FIBER BRAGG GRATING SENSORS FOR TRACKERS SMART Application

FIBER BRAGG GRATING SENSORS FOR TRACKERS SMART- Application to Belle II Vertex Detector LC 2013 , Tracking Vertex session, Desy May 30 th 2012 D. Moya, I. Vila, A. L. Virto, E. Curras , A. Ruiz Instituto de Física de Cantabria M. Frovel, J. G. Carrión Instituto Nacional de Técnica Aeroespacial A. Oyanguren, C. Lacasta, P. Ruiz Instituto de Física corpuscular David Moya Martín, IFCA (CSIC-UC)

Outline n n n Introduction to Fiber Bragg Grating (FBG) optical sensors The Belle II vertex detector (VXD): A FBG-based real time monitoring for VXD. q q n Displacement transducers (omega and L-shape) n Manufacturing n Thermal and displacement calibration n Humidity, Nitrogen sensitivity Environmental measurements on PXD-SVD thermal closure. Summary D. Moya, LC 2013 Tracking-Vertex session, Desy May. 30 th 2013

OFS & FBG advantages § FBG sensors are strain and temperature sensors inscribed in the core of an optical fiber (length ≈ 10 mm, diameter ≈ 200 um). Attributes: q Immunity against: n n q q q High electromagnetic fields, high voltages. High and low temperatures. ((4 K to 1200 K). Characterized up to high radiation dose (1. 5 Grads) Small footprint, Light-weight, flexible, low thermal conductivity. Low-loss, long-range signal transmission(“Remote sensing”) Wavelength encoded ( multiplexing capability) Embedding in composite materials. Mass producible at reasonable costs. D. Moya, LC 2013 Tracking-Vertex session, Desy May. 30 th 2013

FOS for environmental and structural monitoring industry driven technology D. Moya, LC 2013 Tracking-Vertex session, Desy May. 30 th 2013

, A FBG-BASED REAL TIME ESTRUCTURAL AND ENVIROMENTAL MONITOR FOR BELLE-II VXD. Strip Vertex detector (microstrips) ≈300 mm DEPFET PIXELS ≈900 mm D. Moya, LC 2013 Tracking-Vertex session, Desy May. 30 th 2013

, A FBG BASED REAL TIME ESTRUCTURAL AND ENVIROMENTAL MONITOR FOR BELLE-II VXD. Cooling block screwed to ring, attached to the beam pipe CO 2 inlet Air inlet Cooling block DEPFET PIXEL D. Moya, LC 2013 Tracking-Vertex session, Desy May. 30 th 2013

, FBG Real time monitor for VXD n Relative PXD-SVD radial positioning. q q n Using displacement FOS-based custom made transducers ( Omega and L-shape) Radial compressions and expansions (PXD and SVD are mechanically independent) are a mode to which track-based alignment has a poor sensitivity. Environmental measurement inside the PXDSVD thermal envelope q q PXD & SVD cooled with CO 2 and forced air; inside thermal envelop we will have a dry atmosphere ( Dry air or Nitrogen). Distributed FBG network for temperature and humidity monitoring. D. Moya, LC 2013 Tracking-Vertex session, Desy May. 30 th 2013

, _Displacement-Strain n n transducers The idea is to monitor online PXD-SVD relative displacement using a tiny CFRP structure with FBG sensors embedded. Four Omega Shapes(W 1, W 2, W 3 and W 6) and three L shapes (L 1, L-2, L-3) have been manufactured and calibrated with temperature and displacement L-shapes attached to Belle II PXD Contact surface Locked part FBG sensors L-shapes Contact ball D. Moya, LC 2013 Tracking-Vertex session, Desy May. 30 th 2013

, VXD FOS Monitor Timeline 2009 Oct FOS Monitor proposal 2010 Jan Omega-shape proposal 2010 Oct. FOS radiation hardness study (1. 5 GRads , 3. 3 1015 p/cm 2) 2011 January First omega mechanical dummies 2011 March Test in depfet mock-up at IFIC 2011 Sept. FOS radiation hardness study ( 10 Mrads ) 2011 Dec Proof-of-comcept-prototype omega 2012 Feb Omega calibration. 2012 March New transducer design L-shape 2012 May Test in depfet mock-up at IFIC 2012 October L –shape calibration (resolution less 1 um , accuracy≈10 um ) 2013 May Test in deftet mock-up at IFIC (N 2 atmosphere) q 2013 June-July Omegas and L-s irradiation ELSA q 2014 January commissioning at PXD-SVD common test beam D. Moya, LC 2013 Tracking-Vertex session, Desy May. 30 th 2013

Omega Shapes & L-shapes Manufacturing Omega Shape Omega CFRP layout FO output Aluminum Cask L-Shape Kapton Film FO output Aluminum Cask Aluminum support base Steel cask for connectors protection Kapton Film D. Moya, LC 2013 Tracking-Vertex session, Desy May. 30 th 2013

Omega Shapes an L-shapes Manufacture Process Connectors protection Vacuum Pump connection Omega Shape Protection output cable from the omega Omega Shape All inside an oven Vacuum bag D. Moya, LC 2013 Tracking-Vertex session, Desy May. 30 th 2013

Thermal calibrations and temperature compensation § Omega and L-shapes were calibrated using a thermocouples calibrator. They were calibrated to three different temperatures, and the calibration was repeated three times. § The sensitivity of three sensors was constant and near the same (difference<0. 6%) Maximum error < 3 pm (0. 3 ºC) Error X 10 — Error X 10 Trivial approach to temperature compensation with subtraction of top and bottom sensor readout ( Destimator) D. Moya, LC 2013 Tracking-Vertex session, Desy May. 30 th 2013

Interferometric calibration set-up § We have setup a Michelson interferometer for the L-shape calibration § The use of the Interferometer allow us to measure the displacement with a resolution and an stability below the micron. Retro reflector Laser beam Beam spliter L-shape Beam spliter Contact ball Micrometric stage Contact surface L-shape D. Moya, LC 2013 Tracking-Vertex session, Desy May. 30 th 2013

L-shape stability study § The stability of the L shape was measured during near two and a half hours at a compression of near 0. 2 mm. . RMS ≈ 0. 6 um D. Moya, LC 2013 Tracking-Vertex session, Desy May. 30 th 2013

L-shape repeatability study § Repeatability measurements done with the interferometer § The L-shape was compressed between 0. 3 mm and 1. 1 mm and this process was repeated seven times with a repositioning better than 1 um according to the interferometer readout. § Tables show the deviation with respect to the initial position 0. 3 mm displacment Nº of measure Destimator desviation (um) 1 2 3 4 5 6 7 1. 77 5. 08 6. 85 6. 61 7. 02 8. 39 9. 35 rms(um) 2. 46 um 1. 1 mm displacment Nº of measure Destimator desviation (um) 1 2 3 4 5 6 -16. 94 -9. 11 11. 21 11. 45 5. 65 -12. 34 rms 12. 60 um D. Moya, LC 2013 Tracking-Vertex session, Desy May. 30 th 2013

L-shape Calibration: Response vs. displacement Linear fit Residuals (mm) Reconstructed Displacement (mm) § The L-shapes have been compressed in steps of 0. 1 mm up to a total compression of 1 mm § The L-shape has a resolution below one micron. D. Moya, LC 2013 Tracking-Vertex session, Desy May. 30 th 2013

L-shape Calibration problem § Some problems due to contact roughness surface on the uncompressing displacement. D. Moya, LC 2013 Tracking-Vertex session, Desy May. 30 th 2013

L-shape humidity and Nitrogen sensitivity § The L-shape was introduced in IFIC PXD mockup and some humidity and Nitrogen cycles where done § We concluded that the L-shape is not sensitive to humidity changes or Nitrogen concentration. D. Moya, LC 2013 Tracking-Vertex session, Desy May. 30 th 2013

, Environmental monitoring at IFIC Defpet Set-up FBG on Cu ladder L Shape Omega Shape FBG on sensor Reference FBG sensors Humidity sensor D. Moya, LC 2013 Tracking-Vertex session, Desy May. 30 th 2013

, Summary … n n n A displacement and environmental monitor for the Belle II vertex detector based on Fiber Bragg Grating optical sensors was introduced. A miniaturized, application specific, displacement transducer (L-shape) was designed, developed and (almost) fully characterized with a displacement resolution of about 1 um. L-shape experimentally proven not sensible to the environmental conditions of Belle-II thermal envelope: changes in HR%, temperature and N 2 concentration. D. Moya, LC 2013 Tracking-Vertex session, Desy May. 30 th 2013

… and work in progress § Roughness of the contact surface with the sensor tip limits sensor precision (repeatability) and accuracy (few tens of microns). Optimize the L-shape tip and contact surface § 2013 June-July, new Irradiation at Elsa with electrons up to 10 Mrads § 2014 January, partial of the system commissioning at PXD-SVD common test beam @ DESY. D. Moya, LC 2013 Tracking-Vertex session, Desy May. 30 th 2013

BACK - UP D. Moya, LC 2013 Tracking-Vertex session, Desy May. 30 th 2013

, _Bragg n n grating sensor basics FOS monitoring is an standard technique in aeronautic and civil engineer Kkkk Mechanical sensitivity Thermal sensitivity D. Moya, LC 2013 Tracking-Vertex session, Desy May. 30 th 2013

_Bragg grating Multiplexing D. Moya, LC 2013 Tracking-Vertex session, Desy May. 30 th 2013

_Basic Interrogating Unit Optical Spectrum Analyzer The number of different Braggs is more than 100; moreover by using an optical switching we can. Bandwidth use tens of sensing fiber Large Light source 1 x 2 coupler B 1 B 2 Bn B 3 D. Moya, LC 2013 Tracking-Vertex session, Desy May. 30 th 2013